My husband installed a new direct vent gas fireplace. Our problem is that even with the aperture open a full half inch, the logs still get black spotting when the fire is turned up more than a glow. The manufacturer says we must have installed vent wrong - must not have locked all pieces into place - but hubby insists (and I did watch him do it) that he twist-locked them properly into place. I'm frustrated. If I burn the fire real low, the black spots burn off. If this helps any, the black spots are larger and cover more surface area on the logs if the temp and humidity are higher. I sure would appreciate a response to this - I love my fireplace but this upsets me.

Answer:

Something is not quite right. Gas fireplaces should not be a DIY project for reasons like this. It might be great if everything works fine, but if something is wrong (as it often is), it might be difficult to troubleshoot. Here's some possibilities: